Process for the preparation of inhibitors



I PROCESS FOR THE PREPARATION 0F INHIBITORS May 26, 1936. J. D. RuYs ErAL PROCESS FOR THE APREPARATION OF INHIBITORS Filed April 3, 1935 2Sheets-Sheet into the sulfate.

Patented May 26, 1936 UNll'ED STATES 2,042,412 PROCESS FOR THEPREPARATION OF lNHIB Jan D. Ruys and Calif., assignors pany, SanFrancisco, Delaware Application April 3,

Russell L. Kittle, Pittsburg, to Shell Development ITORS Com- Calif., acorporation of -1925, serial No. 14,544

9 Claims. l(Cl. L18-8.1)

This invention relates to agents for the prevention of the corrosionwhich occurs upon the surface of metals when removing undesirable filmsas in the pickling of steel.

When an article made of a material such as steel is heat processed or issubjected to a prolonged atmospheric exposure, undesirable oxide lms4form on the surface of the article. Those films are known respectivelyas mill-scale and rust and usually consist of various oxides of iron. Itis desirable to remove these lms prior to galvanizing or other finishingprocess, and for this purpose the article is subjected to a treatmentknown as pickling, The pickling operation usually comprises placing thearticle in a tank or vat containing dilute sulfuric acid. To facilitatethe action the acid is usually hot. The acid acts upon the mill-scaleand rust converting it However, the acid also acts upon the metal sothat considerable metal may be lost before all the mill-scale and rustis removed from al1 parts of the article being treated. A considerablewaste of acid also results.

Various substances have been proposed for adding to the pickling bath sothat the action of the acid will be limited to the mill-scale and rust,These substances have been termed inhibitors since they greatly reducethe action of the acid upon the bare metal while at the same time onlyslightly reducing the action of the acid upon the oxide film. Among themany inhibitors used may be mentioned acid wastes resulting from thetreatment of coal tar or petroleum distillates. These are known as acidsludges and many of them contain nitrogen bases.

There are several disadvantages in employing these materials asinhibitors. Due to the insolubilityy of part of the inhibitor in thepickling bath a scum is often formed on the surface of the acid. Thisscum adheres to the articles being taken out of the bath, besidessticking to the sides of the pickling bath. The existing inhibitorsproduced from acid sludge have a most disagreeable odor often soobnoxious as to entirely prevent their use.

It is an object of our invention to devise a process for producinginhibitor from petroleum acid sludges having superior inhibitingproperties tothose heretofore produced. It is another object to devise aprocess whereby an inhibitor having no disagreeable odor may be producedfrom acid sludge. A further object is to produce an. inhibitor frompetroleum sludges which is completely soluble in the pickling bath. Astill further object is to prepare an intermediate for the preparationof organic compounds. The other objects of our invention will beapparent to those skilled in the art from the following detaileddescription of a preferred form of our invention throughout whichreference is made to the accompanying drawings of whicht- Fig. I is achart of the process steps involved.

Fig. II is a diagrammatic iiow sheet of appa-` ratus suitable forcarrying out the process.

Referring to Figure I acid sludge resulting from the treatment ofpetroleum distillates is first neutralized with ammonia preferably in asaturated solution of ammonium sulfate. As a result the sulfuric acid inthe acid sludge is neutralized producing ammonium sulfate. Certainorganic sulfates present in the acid sludge are also acted upon by theammonia forming ammonium sulfate and releasing organic oily material.This latter material together with other oil originally present in theacid sludge collects on the surface of the aqueous liquid from which itis removed. Throughout the rest of this specification and claims, werefer to this separated oily material resulting from the neutralizationof acid sludge as recovered oil.

If necessary, the recovered oil is heated to a sufficiently hightemperature so that its iluidity is sufficiently increased to facilitatefurther treatment. Thereafter an aqueous solution of ammonia is added tothe recovered oil to produce free ammonia in the container in suchamounts that a small excess of ammonia exists in the mixture. Aftersufficient time has elapsed the liquid will separate into two layers.The aqueous layer of ammonia extract is drained off to a secondcontainer. The effect of this ammonia treatment is to extract certainorganic material which we have called acid oil. The remaining oilymaterial in the container is next treated with sulfuric acid fandpreferably ammonium sulfate. This treatment extracts basic compoundsfrom the oily material. In our work we have preferred to use ammonia,sulfuric acid and ammonia sulfate as treating agents but the process maybe executed equally well with other alkalis, acids and alkaline saltsrespectively. The basic compounds extracted from the oil are mostlynitrogen compounds and will be referred to hereafter as nitrogen bases.It will thus be seeen that we now have an ammonia extract containingacid oil and an acid extract containing nitrogen bases. The two extractsare next mixed one with the other. As a result of this mixing the acidoil and nitrogen bases become released from their carriers and combinewith one another forming a layer which we have called acid oil nitrogenbase. This product is removed and diluted with water resulting infurther stratification of the material. The upper layer called inhibitorsolution is separated from the other liquor called residual acid oilnitrogen base. Ammonium sulfate either as a solid salt or asconcentrated aqueous solution is added to the inhibitor solution and hasthe effect of concentrat- (9) and (9a).

ing the inhibitor by its salting out eiect. Other salts may be used forthe same purpose. The finished product is removed from the surface ofthe tank.

This product is soluble in sulfuric acid, possesses no disagreeablesmell and has good inhibiting properties. Instead of concentrating theinhibitor from the inhibitor solution by adding ammonium sulfate asabove mentioned, the inhibi-i tor solution could be used directly assuch, however, its inhibiting qualities will be proportional, to theconcentration of the finished inhibitor in solution.

Referring to Fig. II which shows in elevation apparatus suitable forcarrying out our process, a required amount of recovered oil produced byneutralizing acid sludge with ammonia is introduced into the firstagitator (I) from pipe (2) controlled by valve (3). Water is then runinto the agitator (I) from pipe (4) controlled by valve (5). Thereafter,amounts of ammonia gas are passed into the agitator through pipe (6)which extends to the bottom of said agitator (I). The ammonia ow iscontrolled by a valve (40). The ammonia gas entering stirs the mixtureso that a mechanical stirrer can be dispensed with. During the additionof ammonia gas the contents of the agitator are circulated by pump (8)through lines (9) and (9a). Instead of using ammonia gas and water, wemay, of course, use an aqueous ammonia solution of desiredconcentration. After sufficient ammonia has been passed in so that theresulting mixture is slightly ammoniacal, the ammonia valve is closed.After a short period a layer of ammonia extract will gravitate to thebottom of the agitator (I). This extract is pumped from the firstagitator (I) to the second agitator ('l) by means of pump (8) and line(9) controlled by Valve (I0). After the ammonia extract has been drawnoff the valve (I0) is closed. To the oily material now remaining in thefirst agitator amounts of sulfuric acid and ammonium sulfate solutionfrom line (I I) controlled byvalve (I2) are added and the contents ofthe agitator are circulated by means of pump 8) through lines As aresult a layer of acid extract containing nitrogen bases settles to thebottom of the vessel. This acid extract is pumped to the second agitator(1) through line (9) by opening valve (I0) and starting up pump (8).After the acid extract has been transferred to the second agitator, thevalve (I0) is closed and the remaining oily material is run to storagetank (I3) through pipe (I4) by opening valve (I5). This material can beused as fuel under boilers.

The ammonia extract and the acid extract are next mixed in the secondagitator (1) by means of a stirrer (I6). As a result of this admixturethe acid oil of the ammonia extract combines with some of the nitrogenbases of the sulfuric acid extract forming a layer of acid oil nitrogenbase material on a layer of nitrogen bases dissolved in a sulfuric acidand ammonium sulfate solution. (This latter we have called nitrogen basesolution.) The nitrogen base solution is withdrawn from the secondagitator (1) to'storage tank (I1) by means of pipe (I8) by opening valve(I 0). This nitrogen base solution can be used as a source of nitrogenbases by subsequent treating. To acid oil nitrogen base material4remaining in the second agitator is added water from line (4) byopening valve (20). After sumcient water has been run in, the valve (20)is closed and the contents of the agitator mixed by means of stirrer(I6). After thorough mixing the material separates into two layers uponstanding. The lower layer called residual acid oil nitrogen base is runto a storage tank (2l) through pipe (22) by opening valve (23). Thevalve (23) is closed after all the lower layer has 5 been withdrawn andthe upper layer called inhibitor solution is pumped into the thirdagitator (24) by means of pump (25) by means of pipe (26) by openingvalve (21) An amount of solid ammonium sulfate is then dumped into thisthird agitator (24) from salt elevator (28). The stirrer (29) is nextoperated to cause the contents to be thoroughly mixed. After sufficienttime ler settling has elapsed the inhibitor rises to the top of theremaining liquor, which liquor consists of ammonium sulfate solution.This ammonium sulfate solution is then drawn off to a storage tank (30)by pipe (3|) by opening valve (32). When the ammonium sulfate solutionhas all run off, valve (32) is closed and valve (33) is opened allowingthe inhibitor to run to its storage tank (34) by pipe (35).

The ammonium sulfate solution in tank (30) can be mixed with sulfuricacid in the necessary proportions for introducing into the firstagitator (I) by pumping the same in controlled amounts into line (I I)by means of pump (36) and line (31). The proportion of ammonium sulfateto sulfuric acid can be controlled by regulation of valves (38) and(39).

'Ihe inhibitor as produced by our process is soluble in dilute sulfuricacid, has no unpleasant smell and has been found to have inhibitingproperties equal to Rodine No. 110 which has the following analysis:

Per cent symmetrical Z-methyl phenyl thiourea 27.5 Sodium chloride 67.5Glue 5.0

Our inhibitor is used in the same manner as 40 Rodine No. 110".

'I'he usual practice in the pickling of steel plates for the manufactureof tin plates is to make a pickling bath of desired sulfuric acidconcentration, mix in the necessary quantity of inhibitor and dip theplates into the bath in batches. As the acid is consumed, more 66 B.sulfuric acid and inhibitor areadded to maintain the concentrationwithin the desired limits.

As an example of commercial test with our product the following isgiven:

Total H2804 66 B.v used 4840 lbs. Acid concentration of bath 7% HzSO4Inhibitor used- 4,550 ce 9.60 lbs. Steel pickled 66.07 long tons Amountof inhibitor used per long ton of steel treated .145 lb.

As a specific example of operating conditions 50 of our process thefollowing example is given: The recovered oil was obtained byneutralizing acid sludge (resulting from the treatment of pressuredistillate, a cracked petroleum product) with ammonia. The recovered oilat a temperature of approximately 80 C. was mixed with approximatelyone-seventh its volume of water at the same temperature tov which 2% ofits weight of gaseous ammonia was added during the mixing of theliquids. After mixing and settling the ammonia extract was separatedfrom the oil.

A hot, nearly saturated solution of ammonium sulfate and 67% sulfuricacid was next added to the oil, the ratio of the volume of ammoniumsulfate solution to sulfuric acid being kept at about 6:1. Approximately'72.5 gr. of sulfuric acid were required to extract the nitrogen basesfrom a liter of recovered oil. The resulting acid extract after settlingwas removed and mixed with the ammonia extract. Upon standing an aqueoussolution of nitrogen bases separated from the "acid oil nitrogen base.Thereafter the acid oil nitrogen base was mixed with twicethe amount ofwater which caused a separation in two layers. The upper layer was mixedwith enough solid ammonium sulfate to render the whole approximatelysaturated. The inhibitor product was separated from the ammonium sulfatesolution by skimming.

Our product besides being an excellent inhibitor for the pickling ofsteel has been found to have value as an insecticide. 1

It should be borne in mind that the above is by way of example and thatthe exact operating conditions will vary with different sludges. It isnot intended that the specific details be regarded as limitations uponthe scope of the invention which is set forth in the appended claims.

We claim as our invention.:

1. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising neutralizing the. acid content of saidsludge, adding alkali to the oily layer produced, removing the resultingalkaline extract, adding acid and alkaline salt to the remaining oil,removing the acid extract produced, mixing said alkaline extract withsaid acid extract, removing the resulting acid oil nitrogen base,hydrolyzing said acid oil nitrogen base whereby a layer of inhibitorsolution is produced, thereafter separating inhibitor from said solutionby means of a suitable salt.

2. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising neutralizing the acid content of saidsludge, adding ammonia to the oily layer produced, removing theresulting ammonia extract, adding sulfuric acid and ammonium sulfate tothe remaining oil, removing the acid extract produced, mixing saidammonia extract with said acid extract, removing the resulting acid oilnitrogen base, hydrolyzing said acid oil nitrogen base whereby a layerof inhibitor solution is produced, thereafter separating inhibitor fromsaid solution by means of ammonium sulfate.

'3. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising neutralizing the acid content of saidsludge, adding ammonia to the oil layer produced, removing the resultingammonia extract, adding sulfuric acid and ammonium sulfate to theremaining oil, removing the acid extract produced, mixing said ammoniaetxract with said acid extract, removing the resulting acid oil nitrogenbase, hydrolyzing said acid oil nitrogen base whereby a layer ofinhibitor solution is produced, thereafter separating inhibitor fromsaid solution.

4. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising,

vneutralizing the acid content of said sludge with ammonia, separatingthevoily material produced, adding ammonia to said oily material,removing the resulting ammonia extract, adding sulfuric acid to theremaining oil, removing the acldextract produced, mixing said ammoniaextract with said acid extract, removing the resulting acid oil nitrogenbase, hydrolyzing said acid oil nitrogen base whereby a layer ofinhibitor solution is produced, thereafter separating inhibitor fromsaid solution by adding ammonium sulfate.

5. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising neutralizing the acid content of saidsludge with ammonia, separating the oily material produced, addingammonia to said o'ly material whereby an ammonia extract is produced,separating the ammonia extract from the remaining oil, adding sulfuricacid to the remaining oil, whereby an acid extract is produced,separating the acid extract from the remaining residual oil, adding saidacid extract to said ammonia extract whereby a layer of acid oilnitrogen base material is produced, removing the acid oil nitrogen basematerial, hydrolyzing the same whereby a layer of inhibitor solution isformed, removing the inhibitor solution and separating inhibitortherefrom by the addition of a concentrated ammonium sulfate solution.

6. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising neutralizing the acid content of saidsludge with ammonia, removing the resulting oily layer, adding ammoniato this oily layer, removing the resulting ammonia extract, addingammonium sulfate and sulfuric acid in the proportion of six partsammonium sulfate to one part sulfuric acid to the remaining oil,removing the resulting acid extract, adding the acid extract to theammonia extract whereby a layer of acid oil nitrogen base material isproduced, hydrolyzing said acid oil nitrogen base material whereby alayer of inhibitor solution is produced, thereafter separating inhibitorfrom said solution.

'7. Process for the manufacture of pickling inhibitor from petroleumacid sludge comprising,

neutralizing the acid content of said sludge with ammonia, extractingacid oil material `from the oily material produced by saidneutralization, then extracting nitrogen base material from said oilymaterial, adding said acid oil material to said nitrogen base materialwhereby an acid oil nitrogen base is produced, adding amounts of waterto said acid oil nitrogen base, separating the upper layer of liquidproduced and adding solid ammonium sulfate to said upper layer, toseparate the inhibitor.

8. The herein described pickling inhibitor obtained by neutralizing theacid content of petroleum acid sludge with ammonia, separating the oilymaterial produced, adding ammonia to said oily material, removing theresulting ammonia extract, adding sulfuric acid to the remaining oil,removing the acid extract produced, mixing said ammonia extract withsaid acid extract, removing the resulting acid oil nitrogen base,hydrolyzing said acid oil nitrogen base whereby a layer of inhibitorsolution is produced, and separating said inhibitor from said solutionby the addition of ammonium sulfate.

9. Process for the manufacture of steel pickling inhibitor frompetroleum acid sludge comprising substantially neutralizing the acidcontent of said sludge. adding a base to the oily layer producedremoving the tract, adding acid and a salt of the alkali earth metalsincluding ammonium, removing the acid extract produced, mixing saidbasic extract with said acid extract, removing the resulting acid oilnitrogen base, hydrolyzing said acid oil nitrogen base whereby a layerof inhibitor solution is produced and thereafter'separating inhibitorfrom said solution by means of a'suitable salt.

JAN D. RUYS.

RUSSELL L. KIITI-E resulting basic ex-

